不多说，直接上干货！

 

　　　下面，是版本1。

 

 

 

 

　　　　下面是版本2。

 

 

 

 

 

              这篇博客，给大家，体会不一样的版本编程。

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

代码

package zhouls.bigdata.myMapReduce.weather;import java.io.DataInput;import java.io.DataOutput;import java.io.IOException;import org.apache.hadoop.io.WritableComparable;public class MyKey implements WritableComparable
     
      {    //WritableComparable,实现这个方法，要多很多    //readFields是读入，write是写出    private int year;    private int month;    private double hot;    public int getYear() {    return year;}    public void setYear(int year) {        this.year = year;    }        public int getMonth() {        return month;    }        public void setMonth(int month) {        this.month = month;    }        public double getHot() {        return hot;    }        public void setHot(double hot) {        this.hot = hot;        }//这一大段的get和set，可以右键，source，产生get和set，自动生成。    public void readFields(DataInput arg0) throws IOException { //反序列化        this.year=arg0.readInt();        this.month=arg0.readInt();        this.hot=arg0.readDouble();    }        public void write(DataOutput arg0) throws IOException { //序列化        arg0.writeInt(year);        arg0.writeInt(month);        arg0.writeDouble(hot);    }    //判断对象是否是同一个对象，当该对象作为输出的key    public int compareTo(MyKey o) {        int r1 =Integer.compare(this.year, o.getYear());//比较当前的年和你传过来的年        if(r1==0){        int r2 =Integer.compare(this.month, o.getMonth());        if(r2==0){            return Double.compare(this.hot, o.getHot());        }else{            return r2;        }        }else{            return r1;        }    }}
     

 

 

 

 

 

 

 

 

 

 

 

 

 

package zhouls.bigdata.myMapReduce.weather;import org.apache.hadoop.io.DoubleWritable;import org.apache.hadoop.io.NullWritable;import org.apache.hadoop.mapreduce.lib.partition.HashPartitioner;public class MyPartitioner extends HashPartitioner
     
      {
   //这里就是洗牌    //执行时间越短越好    public int getPartition(MyKey key, DoubleWritable value, int numReduceTasks) {        return (key.getYear()-1949)%numReduceTasks;//对于一个数据集，找到最小，1949    }}//1949-10-01 14:21:02    34c//1949-10-02 14:01:02    36c//1950-01-01 11:21:02    32c//1950-10-01 12:21:02    37c//1951-12-01 12:21:02    23c//1950-10-02 12:21:02    41c//1950-10-03 12:21:02    27c//1951-07-01 12:21:02    45c//1951-07-02 12:21:02    46c//1951-07-03 12:21:03    47c
     

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

package zhouls.bigdata.myMapReduce.weather;import org.apache.hadoop.io.WritableComparable;import org.apache.hadoop.io.WritableComparator;public class MySort extends WritableComparator{    public MySort(){        super(MyKey.class,true);//把MyKey传进了    }    public int compare(WritableComparable a, WritableComparable b) {
   //这是排序的精髓        MyKey k1 =(MyKey) a;        MyKey k2 =(MyKey) b;        int r1 =Integer.compare(k1.getYear(), k2.getYear());        if(r1==0){
   //年相同        int r2 =Integer.compare(k1.getMonth(), k2.getMonth());        if(r2==0){
   //月相同            return -Double.compare(k1.getHot(), k2.getHot());//比较气温        }else{            return r2;        }        }else{            return r1;        }    }}

 

 

 

 

 

 

 

package zhouls.bigdata.myMapReduce.weather;import org.apache.hadoop.io.WritableComparable;import org.apache.hadoop.io.WritableComparator;public class MyGroup extends WritableComparator{    public MyGroup(){        super(MyKey.class,true);//把MyKey传进了}    public int compare(WritableComparable a, WritableComparable b) {
   //这是分组的精髓        MyKey k1 =(MyKey) a;        MyKey k2 =(MyKey) b;        int r1 =Integer.compare(k1.getYear(), k2.getYear());    if(r1==0){        return Integer.compare(k1.getMonth(), k2.getMonth());    }else{        return r1;    }    }}

 

 

 

 

 

 

package zhouls.bigdata.myMapReduce.weather;import java.io.IOException;import java.text.ParseException;import java.text.SimpleDateFormat;import java.util.Calendar;import java.util.Date;import org.apache.hadoop.conf.Configuration;import org.apache.hadoop.fs.FileSystem;import org.apache.hadoop.fs.Path;import org.apache.hadoop.io.DoubleWritable;import org.apache.hadoop.io.NullWritable;import org.apache.hadoop.io.Text;import org.apache.hadoop.mapreduce.Job;import org.apache.hadoop.mapreduce.Mapper;import org.apache.hadoop.mapreduce.Reducer;import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;import org.apache.hadoop.mapreduce.lib.input.KeyValueTextInputFormat;import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;public class RunJob {//    1949-10-01 14:21:02    34c WeatherMapper//    1949-10-02 14:01:02    36c//    1950-01-01 11:21:02    32c    分区在MyPartitioner.java //    1950-10-01 12:21:02    37c//    1951-12-01 12:21:02    23c    排序在MySort.java//    1950-10-02 12:21:02    41c//    1950-10-03 12:21:02    27c    分组在MyGroup.java//    1951-07-01 12:21:02    45c//    1951-07-02 12:21:02    46c    再，WeatherReducer//    1951-07-03 12:21:03    47c//key：每行第一个隔开符（制表符）左边为key，右边为value    自定义类型MyKey，洗牌，        static class WeatherMapper extends Mapper
     
      {    SimpleDateFormat sdf =new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");    NullWritable v =NullWritable.get();//    1949-10-01 14:21:02是自定义类型MyKey，即key//    34c是DoubleWritable，即value    protected void map(Text key, Text value,Context context) throws IOException, InterruptedException {    try {        Date date =sdf.parse(key.toString());        Calendar c =Calendar.getInstance();        //Calendar 类是一个抽象类，可以通过调用 getInstance() 静态方法获取一个 Calendar 对象，        //此对象已由当前日期时间初始化，即默认代表当前时间，如 Calendar c = Calendar.getInstance();            c.setTime(date);        int year =c.get(Calendar.YEAR);        int month =c.get(Calendar.MONTH);        double hot =Double.parseDouble(value.toString().substring(0, value.toString().lastIndexOf("c")));        MyKey k =new MyKey();        k.setYear(year);        k.setMonth(month);        k.setHot(hot);        context.write(k, new DoubleWritable(hot));    } catch (Exception e) {        e.printStackTrace();    }    }}    static class WeatherReducer extends Reducer
      
       {    protected void reduce(MyKey arg0, Iterable
       
         arg1,Context arg2)throws IOException, InterruptedException {        int i=0;        for(DoubleWritable v :arg1){        i++;        String msg =arg0.getYear()+"\t"+arg0.getMonth()+"\t"+v.get();//"\t"是制表符        arg2.write(new Text(msg), NullWritable.get());                if(i==3){                    break;                }        }    }}public static void main(String[] args) {    Configuration config =new Configuration();//    config.set("fs.defaultFS", "hdfs://HadoopMaster:9000");//    config.set("yarn.resourcemanager.hostname", "HadoopMaster");//    config.set("mapred.jar", "C:\\Users\\Administrator\\Desktop\\wc.jar");//    config.set("mapreduce.input.keyvaluelinerecordreader.key.value.separator", ",");//默认分隔符是制表符"\t"，这里自定义，如","    try {        FileSystem fs =FileSystem.get(config);        Job job =Job.getInstance(config);        job.setJarByClass(RunJob.class);        job.setJobName("weather");        job.setMapperClass(WeatherMapper.class);        job.setReducerClass(WeatherReducer.class);        job.setMapOutputKeyClass(MyKey.class);        job.setMapOutputValueClass(DoubleWritable.class);        job.setPartitionerClass(MyPartitioner.class);        job.setSortComparatorClass(MySort.class);        job.setGroupingComparatorClass(MyGroup.class);        job.setNumReduceTasks(3);        job.setInputFormatClass(KeyValueTextInputFormat.class);//    FileInputFormat.addInputPath(job, new Path("hdfs://HadoopMaster:9000/weather.txt"));//输入路径，下有weather.txt//    //    Path outpath =new Path("hdfs://HadoopMaster:9000/out/weather");        FileInputFormat.addInputPath(job, new Path("./data/weather.txt"));//输入路径，下有weather.txt    Path outpath =new Path("./out/weather");    if(fs.exists(outpath)){        fs.delete(outpath, true);    }    FileOutputFormat.setOutputPath(job, outpath);        boolean f= job.waitForCompletion(true);        if(f){        }    } catch (Exception e) {        e.printStackTrace();    }    }}
       
      
     

 

 

 

 

 

 

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